1. Field of the Invention
The present invention relates to a metal or resin tube joint used for water pipes and the like.
2. Description of the Related Art
FIG. 5 shows one example of a tube joint for jointing ends of axially opposed metal or resin tubes 1, 1 such that extending and contracting function and flexible function are provided. The tube joint includes a joint body 2 and a pair of push rings 3 and 3, and they are fastened by fastening means 4 which are T-shaped bolts and nuts. The joint body 2 includes opposed flange-like projections 2a and 2a, and a cylindrical barrel portion 2b which is integrally formed such as to swell between the projections 2a ,2a. Each of the projections 2a is provided at its inner periphery with a receiving port 2c whose diameter becomes wider toward its end. The push ring 3 also includes a projection 3a, the joint body 2 is located at the outer periphery between the joint tubes 1 and 1 while leaving a circumferential gap, and the push rings 3, 3 are disposed at the opposite ends, and the ends are fastened by the fastening tools 4. By fastening using the fastening tools 4, a rubber packing 5 set between the joint body 2 and each of the push rings 3 is pushed by surfaces of the push rings 3 and connected to the receiving port 2c in wedge form, and is also contacted to an outer peripheral surface of the joint tube 1 under pressure. With this, watertightness is established so that liquid flowing through the joint tubes 1, 1 should not leak outside.
As shown in FIG. 5 also, the conventional tube joint has a structure that if the fastening tools 4 are fastening, the rubber packing 5 can freely be fastened. Therefore, even if a tolerance fastening torque is indicated, the fastening state varies depending upon operators, and torque can not be controlled.
The cross section of the rubber packing 5 (JIS K6353; A type) shown in FIG. 5 is tapered, and any portions thereof are relatively hard, and homogeneous having the same resilience. Therefore, strong pressing force can not be obtained, and the sealing ability is not sufficient. As a rubber packing which can be used in the tube joint shown in FIG. 5, there exists one having soft portion (JIS K6353; K type), but a volume of the rubber packing occupied by the soft portion is smaller than that occupied by the hard portion, and there is a room for improvement of the resiliently deforming and sealing abilities.
The present invention has been accomplished to overcome the above-described conventional problems, and it is the first object of the invention to provide a tube joint in which the operation can easily be controlled by always obtaining a constant fastening force irrespective of magnitude of the fastening force, and the sealing ability is always reliably obtained constantly. It is another object to provide a tube joint in which the sealing ability is stronger than that of the prior art so that a constant sealing ability or greater can be reliably obtained.
To solve the above problems, a tube joint of the present invention comprises: a pushing ring provided at its outer periphery with a projection and fitted to an outer periphery of one end of a joint tube; a tube or a joint body provided at is side opposed to the pushing ring with a projection opposed to the projection of the pushing ring, the tube or the joint body having a receiving portion which is widened toward the pushing ring and the tube or the joint body being fitted to an outer periphery of the joint tube with a peripheral gap left therebetween; a fastening tool capable of moving the pushing ring in a direction of the tube or the joint body; a packing provided between inner and outer side of the tube or the joint body and the joint tube, and fitted through the receiving portion by its own resilient deformation by operation of the fastening tool; and a spacer inserted between the pushing ring and the tube or the joint body to limit a distance between the pushing ring and the tube or the joint body to a constant value.
With this structure, since the spacer for limiting the distance between the pushing ring and the tube or the joint body is inserted between the pushing ring and the tube or the joint body, the packing can always obtain a constant fastening force irrespective of the magnitude of the fastening force and therefore, the packing which is prone to be unstable due to the resilient deformation can always be fastened constantly, the operation is facilitated, the operation can easily be controlled, and since the packing may be fastened to the utmost, the sealing ability can always be obtained reliably and constantly.
It is preferable that the spacer is an independent ring provided between the pushing ring and the tube or the joint body.
With this structure, since the spacer is the independent ring, i.e., a spacer ring provided between the pushing ring and the tube or the joint body, the packing can be pushed by the entire ring uniformly as compared with a case in which the packing is pushed directly by the pushing ring whose portion in the circumferential direction can fasten using split mold, and the sealing ability is enhanced, which is convenient.
Further, a tube joint of the invention comprises: a pushing ring provided at its outer periphery with a projection and fitted to an outer periphery of one end of a joint tube; a tube or a joint body provided at is side opposed to the pushing ring with a projection opposed to the projection of the pushing ring, the tube or the joint body having a receiving port which is widened toward the pushing ring and the tube or the joint body being fitted to an outer periphery of the joint tube with a peripheral gap left therebetween; a fastening tool capable of moving the pushing ring in a direction of the tube or the joint body; a packing provided between inner and outer side of the tube or the joint body and the joint tube, and fitted through the receiving portion by its own resilient deformation by operation of the fastening tool; and a spacer inserted between the pushing ring and the tube or the joint body to limit a distance between the pushing ring and the tube or the joint body to a constant value, and the spacer being deformed by fastening operation of the fastening tool, thereby bringing the pushing ring and the tube or the joint body into abutment against each other.
With this structure also, the spacer is deformed by the fastening operation by the fastening tool, the pushing ring and the tube or the joint body abut against each other, the packing can always obtain a constant fastening force irrespective of the magnitude of the fastening force and therefore, the packing which is prone to be unstable due to the resilient deformation can always be fastened constantly, the operation is facilitated, the operation can easily be controlled, and since the packing may be fastened to the utmost, the sealing ability can always be obtained reliably and constantly.
It is preferable that the spacer is an independent resin ring provided between the pushing ring and the tube or the joint body, and is provided with an alignment projection.
With this structure, the packing can be pushed by the entire ring uniformly as compared with a case in which the packing is pushed directly by the pushing ring whose portion in the circumferential direction can fasten using split mold, and the sealing ability is enhanced. In addition to this, when the fastening tool is fastened, since it is made of resin, it is deformed easily, the spacer should not deviated laterally by the operation of the alignment projection and therefore, the packing should not be deformed, these can be disposed easily, and the operation is facilitated, which is convenient.
Further, a tube joint of the invention comprises: a pushing ring provided at its outer periphery with a projection and fitted to an outer periphery of one end of a joint tube; a tube or a joint body provided at is side opposed to the pushing ring with a projection opposed to the projection of the pushing ring, the tube or the joint body having a receiving portion which is widened toward the pushing ring and the tube or the joint body being fitted to an outer periphery of the joint tube with a peripheral gap left therebetween; a fastening tool capable of moving the pushing ring in a direction of the tube or the joint body; and a packing provided between inner and outer side of the tube or the joint body and the joint tube, and fitted through the receiving portion by its own resilient deformation by operation of the fastening tool, an inner periphery of the packing, in its natural state, being greater in diameter than an outer periphery of the joint tube.
With this structure, since the inner periphery of the packing, in its natural state, is greater in diameter than the outer periphery of the joint tube, the packing can be fitted to the joint tube easily, and can be pushed in without excessive resistance, a constant or greater sealing ability can reliably be obtained, which is convenient.
It is preferable that a deep portion of the receiving port at its constricted side is a cylindrical surface parallel to the joint tube, a soft portion of the packing is greater than a hard base of the packing in volume, a tip end of the soft portion is rounded in cross section so that the tip end is resiliently deformed in the parallel cylindrical surface and is fitted in under pressure.
With this structure, the deep portion of the receiving port at its constricted side is the cylindrical surface parallel to the joint tube, the tip end of the soft portion is rounded in cross section so that the tip end is resiliently deformed in the parallel cylindrical surface and is fitted in under pressure. Therefore, when the packing extends, contracts or bent, it is convenient because the seal holding function is stably exhibited. Further, since the soft portion of the packing is greater in volume than the hard base, the sealing ability is greater than that of the prior art, a strong self sealing ability is exhibited, and stronger sealing ability can be exhibited.
It is preferable that the base of the packing at the side of the pushing ring and a tip end of the packing at the side of the tube or the joint body are made of the same or different material, and if the base and the tip end are made of different material, the base is a hard portion and the tip end at the side of the tube or the joint body is a soft portion.
With this structure, if the base and the tip end are made of the same material, they can be formed integrally, the producing cost can be reduced, which are convenient, and if the base is a hard portion and the tip end at the side of the tube or the joint body is a soft portion, the pressure from the pushing ring is reliably transmitted to the hard portion, and the soft portion of the tip end is effectively pressed in, and this pressed in state is effectively held by the hard portion, the sealing ability is exhibited more effectively, which are convenient.
It is preferable that the tube joint further comprises a spacer inserted between the pushing ring and the tube or the joint body to limit a distance between the pushing ring and the tube or the joint body to a constant value. With this structure, the packing can always obtain a constant fastening force irrespective of the magnitude of the fastening force, which is convenient.